Treatment of spinnerettes



Patented July 5, 1949 TREATMENT OF SPINNERETTES Arthur Cresswell, Stamford, Conn., assignor to American Cyanamid Company, New York, N. Y., a corporation of Maine No Drawing. Application February 27, 1945,

Serial No. 580,081

.2 Claims. (Cl. 188) The present invention relates to the treatment of spinnerettes containing a large number of minute apertures such as are used to jet solutions or suspensions to form filaments.

The invention is particularly concerned with the coating of spinnerettes used for the spinning of protein materials such as soy bean protein, gelatin, casein, collagen, albumin, keratin, and the like.

In the spinning of filaments from protein material it is customary to make a solution or a suspension of the substance of the desired concentration, and jet the same under pressure through a multi-orifice spinnerette into a spin bath to cause solidification, coagulation or regeneration of the protein in a more or less onented fibrous state, which filaments are then pulled away from the spinnerettes to form either a multi-filament or unitary strand as desired. Such spin baths usually include aqueous solutions of high concentrations of ammonium or metallic salts such as ammonium sulfate, zinc sulfate, magnesium sulfate, sodium sulfate and the like.

In the spinning of such protein material, extreme difficulty has been experienced in starting the spinnerette due to the fact that in the starting up operation a quantity of the liquid to be spun leaks through the spinnerette and when it makes contact with the spin bath, covers the outer surfaces of the spinnerette and associated parts in a more or less tightly adherent film. Even though this film may be scraped or cleaned away, difficulty is experienced in that the coagulated or regenerated material tends to form again and clogs the holes of the spinnerette with the result that either the extrusion pressure is inadequate to open them or if they become unplugged, result in a broken filament.

The principal object of the invention, therefore, is to provide a coating on such spinnerettes which are usually composed of stainless steel, Monel metal, gold, platinum, palladium, rhodium, tantalum, or alloys containing some or all of them, which will prevent this initial adhesion of the protein material to the surface of the spinnerette. Unless this phenomenon is avoided, partial or complete clogging of some orifices results, with consequent imperfection of filament production.

A considerable amount of experimentation has been carried on to develop a material suitable for this purpose in the spinning of protein materials as above, beginning with those substances found suitable in the spinning of viscose rayon filaments, such as lauryl pyridinium chloride and cetyl pyridinium chloride or the like dissolved in the spinning bath but such substances are completely without effect in preventing initial adhesion of protein material. Inasmuch as it appears that greasy or Waxy solids might have promise, a number of hydrocarbons such as paraffin, mineral oil and the like, were tried without success. Again, fatty acids such as stearic acid, palmitic acid and the like completely failed to overcome the difilculty. The higher alcohols, such as lauryl alcohol, the higher esters such as stearyl glyceride or palmytyl stearate completely failed to accomplish the desired purpose.

It was not until spin bath insoluble and repellent basic nitrogen compounds containing a long chain alkyl radical having twelve carbon atoms or more were tried that any sort of reasonable success occurred. These compounds, on the other hand, are outstanding in avoiding difiiculties heretofore experienced in starting up operations with proteins.

Where these materials are heavy liquids, they may be applied as such or smeared over the outer surface of the spinnerettes and into the orifices therein. Where the substances are very viscous liquids, plastics or solids, they may be thinned or dissolved with organic solvents known as fat solvents such as volatile hydrocarbons such as benzene, gasoline, and xylol and the chlorinated hydrocarbons such as chloroform, carbon tetrachloride or the like which may be readily volatilized.

Perhaps the most suitable class of materials for this purpose are the phosphatides of which lecithin is preferred. However, sphingomyelins and cephalines may also be used. Other materials eminently satisfactory are stearamide, stearylamine, stearylguanidine, laurylamine, N,N-dimethyldodecylamine, 3-stearoxypropylamine, myristylamine, G-octadecoxypropylamine, N,N'-distearylalanyl amide, as well as the long chain alkyl cyanamides, dicyandiamides, melamines, guanarnines, biguanides, guanylureas and the like where in all cases the alkyl radical has twelve or more carbon atoms.

Where the material is applied to the spinnerette in the form of a dilution or solution, chloroform and benzene are entirely satisfactory. It is preferred to make solutions containing from .01% to even as high as 25% in practice. It only becomes necessary to dip the spinnerette in a dilution or solution of the compound or to apply the same to the spinnerette either as a spray or with a brush and then cause the solvent to evaporate with the required amount of heat. Obviously the heat applied to cause evaporation of the solvent should be well below the melting point of the material used so as not to cause an abnormal fiow which might clog the apertures. It has been found desirable during the solvent evaporation step to maintain a flow of gas such as air, nitrogen, carbon. dioxide or-the like through the spinnerette so as to .keep the apertures from clogging with the coating material, while permitting the formation of a film thereon.

Such a treatment upon evaporation of the solvent deposits a very thin film on the spinnerette closely adherent to the surface thereof.

Such a coated spinnerette notonly avoids the difficulty of the sticking thereto of protein solutions or suspensions in the starting up operations but maintains the spinnerette in a perfectly free flowing state.

It has been found, for instance, that a dilute organic acid solution 0f=..collagen containing from 23-15% of the latter may be satisfactorily extruded through a metal spinnerette as above when coated with a film of lecithin deposited from a chloroform solution thereof, immersed in ,an

aqueous spin bath including ammonium sulfate from 35% to saturation and sufiicient ammonia to maintain the pH of the bath at about 7.8, without initial sticking and for long periods of time without the productionof imperfect filaments.

While the invention has'been described with particular reference .to specific embodiments, it

ganic solution of lecithin and then evaporating the solvent while passing air through the spinlnerette apertures to deposit on the material an adherent film of lecithin while maintaining substantiallyall of the apertures open.

ARTHUR CRESSWELL.

REFERENCES CITED The following referenlces are of record in the file of'this patent:

UNITED STATES PATENTS Number Name Date 2,100,581 Weeldenburg Nov. 30, 1937 2,125,031 Polal: et al. July 26, 1938 2,294,154 Barthelemy et al. Aug. 25, 1942 2,310,207 Bley Feb. 9, 1943 OTHER REFERENCES Hackhs, Chemical Dictionary, 3rd ed. (1944). Blakeston Co., Phila,, Pa. (page 485). Copy in Div. 15. 

